Biomedical subjects

M P Robb

Publications and source records attributed to M P Robb.

At least 19 recordsLinked to original sources

PubMed2001

Acoustic comparison of vowel articulation in normal and reverse phonation.

Acoustic characteristics of the vowels /i,u,a/ produced by adult females and males during normal phonation were compared with the same vowels produced on deliberate ingressive airflow (i.e., "reverse" phonation). Results of the analysis revealed the average fundamental frequency (F0) of reverse phonation to be significantly higher than the corresponding normal phonations. There were no significant differences noted in the vocal tract resonance (F1 and F2 frequency) values for /i/ during normal and reverse phonation. However, the F1 values for /a/ were significantly lower, and the F2 values for /u/ significantly higher, during reverse phonation. The results are discussed with regard to differences in the articulatory control of the speech mechanism during reverse phonation as compared to normal expiratory phonation. Also discussed are the implications of using reverse phonation as a voice management technique.

Adult↗

PubMed2001

A study of sentence stress production in Mandarin speakers of American English.

Acoustic characteristics of American English sentence stress produced by native Mandarin speakers are reported. Fundamental frequency (F0), vowel duration, and vowel intensity in the sentence-level stress produced by 40 Mandarin speakers were compared to those of 40 American English speakers. Results obtained from two methods of stress calculation indicated that Mandarin speakers of American English are able to differentiate stressed and unstressed words according to features of F0, duration, and intensity. Although the group of Mandarin speakers were able to signal stress in their sentence productions, the acoustic characteristics of stress were not identical to the American speakers. Mandarin speakers were found to produce stressed words with a significantly higher F0 and shorter duration compared to the American speakers. The groups also differed in production of unstressed words with Mandarin speakers using a higher F0 and greater intensity compared to American speakers. Although the acoustic differences observed may reflect an interference of L1 Mandarin in the production of L2 American English, the outcome of this study suggests no critical divergence between these speakers in the way they implement American English sentence stress.

Adult↗

PubMed1999

Acoustic examination of preterm and full-term infant cries: the long-time average spectrum.

The acoustic characteristics of crying behavior displayed in 2 groups of newborn infants are reported. The crying episodes of 10 full-term and 10 preterm infants were audio recorded and analyzed with regard to the long-time average spectrum (LTAS) characteristics. An LTAS display was created for each infant's non-partitioned crying episode, as well as for 3 equidurational partitions of the crying episode. Measures of first spectral peak, mean spectral energy, and spectral tilt were revealing of differences between full-term and preterm infants' non-partitioned crying episodes. In addition, the full-term infants demonstrated significant changes in their crying behavior across partitions, whereas the preterm infants changed little across the crying episode. Discussion focuses on possible differences between full-term and preterm infants in their neurophysiological maturity, and the subsequent impact on their speech development. The importance of examining entire crying episodes when evaluating the crying behavior of infants is also discussed.

Anthropometry↗

PubMed1997

Formant frequency development: 15 to 36 months.

Developmental characteristics of formant 1 (F1) and formant 2 (F2) are reported for spontaneous vocalizations produced by four young children. Each child was systematically sampled at between 15 and 36 months of age. Results indicated that both F1 and F2 remained relatively unchanged prior to 24 months of age. Significant decreases in average F1 and F2 occurred between 24 and 36 months. When F1 and F2 values were categorized according to tongue elevation and tongue advancement, the most significant changes were associated with high/back articulations. The pattern of formant frequencies noted in the present group of children appears to reflect developmental changes in vocal tract growth and reconfiguration.

Child, Preschool↗

PubMed1997

Application of an acoustic cry template to evaluate at-risk newborns: preliminary findings.

The durational characteristics of crying episodes produced among two groups of at-risk newborn infants are reported. The groups included preterm infants with diagnosed respiratory problems and preterm infants with diagnosed neurological problems. Each infant's complete crying episode was audio-recorded and acoustically analyzed for overall occurrence of expiratory cry segments, inspiratory cry segments, and nonphonatory 'pause' segments. Remarkable similarity was found across risk groups with regard to the distributional occurrence of the cry features. Results obtained for the at-risk infants were highly similar to those observed for normal full-term newborns. These preliminary findings are taken to suggest that temporal features of newborn crying activity reflect a basic organizational response of the nervous system which is common to both normal and at-risk infants.

Acoustics↗

PubMed1997

An acoustic template of newborn infant crying.

The durational characteristics of 10 normal infant's complete crying episodes are reported. The cries of each child were audiorecorded at 2 days postpartum and acoustically analyzed for overall occurrence of expiratory cry segments, inspiratory cry segments, and nonphonatory 'pause' segments. In general, remarkable similarity was found across infants with regard to the distributional occurrence of the cry features. Discussion focuses on the organization of newborn infant crying behavior within the milieu of a crying episode, as well as the diagnostic implications of these findings.

Crying↗

PubMed1997

Developmental aspects of formant frequency and bandwidth in infants and toddlers.

Average formant frequency and formant bandwidth values are reported in a cross-sectional sample of 20 children between 4 and 25 months of age. With the exception of a slight rise in F1 at 18 months of age, average F1 and F2 values changed little during the time period, while the average bandwidths for F1 (B1) and F2 (B2) were found to significantly decrease as age increased. The pattern observed for both average formant frequencies and formant bandwidths were attributed to developmental reconfiguration of the vocal tract.

Child, Preschool↗

PubMed1997

Vocal tract resonance characteristics of adults with obstructive sleep apnea.

Vocal tract acoustic resonance was evaluated in a group of 10 untreated adult males with diagnosed obstructive sleep apnea (OSA) syndrome compared to 10 non-OSA adult males. Subjects were required to prolong the vowels /i/, /u/ and /a/, which were subsequently submitted to acoustic analysis of formant frequency and formant bandwidth. Results of the formant frequency analysis indicated lower formant values among the OSA group compared to the non-OSA group, for each vowel type. The lower formant frequencies among the OSA group were attributed to greater vocal tract length compared to non-OSA speakers. The corresponding formant bandwidths for each vowel produced by the OSA group were significantly wider compared to the non-OSA group. The wide formant bandwidths were interpreted to reflect significantly greater vocal tract damping in the OSA subjects, resulting from either excessive vocal tract tissue compliance or general size differences in the length and cross-sectional area of the vocal tract. Discussion focuses on the potential applications of acoustic analysis to aid in the diagnosis and follow-up treatment of OSA.

Adult↗

PubMed1996

Vocal fundamental frequency characteristics of infant hunger cries: birth to 12 months.

The vocal fundamental frequency (Fo) characteristics of four infants' hunger cries are reported. The infants were audio recorded at monthly intervals during the first year of life. In general, each infant's Fo increased across the one-year period. The increase in Fo was attributed to the transition from early reflexive crying to intentional vocalization behavior, rather than anatomical and physiological growth influences. Discussion focuses on the regulation of infant crying behavior across the first year of life, as well as the diagnostic implications of these findings.

Aging↗

PubMed1995

Estimation of formant frequencies in infant cry.

The formant frequencies (F1, F2, F3) of normal infant crying were measured using three different estimation techniques: sound spectrography, linear predictive coding (LPC), and power spectrum analysis. Results found all three techniques to be highly similar for estimation of F1. However, the techniques differed significantly in the estimation of F2 and F3. Power spectrum analysis tended to yield the highest F2 and F3 values, while LPC consistently provided the lowest F2 and F3 values. Based on the results of the study, serious questions arise whether formant estimates of cry are accurate or appropriate for use as a metric of infant vocal tract resonance.

Acoustics↗

PubMed1995

Acoustic features of normal-hearing pre-term infant cry.

Acoustic features of expiratory cry vocalizations were studied in 125 pre-term infants prior to being discharged from a level-3 neonatal intensive care unit. The purpose was to describe various phonatory behaviors in infants in whom significant hearing loss could be ruled out. We also compared these results with normal-hearing full-term infants, and evaluated whether linkage exists among acoustic cry features and various anthropometric, diagnostic and treatment variables obtained throughout the peri- and neonatal periods. Our analysis revealed that cry duration was significantly related to total days receiving respiratory assistance. The occurrence of other complex spectral and temporal aspects of acoustic cry vocalizations including harmonic doubling and vibrato also increased in infants receiving some form of respiratory assistance. The presence of harmonic doubling also depended on weight and conceptional age at test. The discussion focuses on the implication of these relationships and directions for future research.

Acoustics↗

PubMed1995

Acoustic correlates of inspiratory phonation during infant cry.

The duration and vocal fundamental frequency (Fo) of inspiratory cries produced by a group of 20 healthy infants were measured. Similar acoustic measures were applied to the cries immediately preceding and following an inspiratory cry as a means of characterizing an inspiratory "event." Results were that the number of inspiratory cries varied considerably from child to child during a complete crying episode. The duration and Fo of inspiratory cries were significantly shorter and higher, respectively, in comparison to cries immediately preceding and following the inspiratory cry. In addition, the gap duration following an inspiratory cry was significantly greater than the pre-inspiratory gap duration. Discussion centers on the anatomical and physiological bases of inspiratory cry phonation. Implications as well as the need to consider the inspiratory portion of crying behavior when examining infants at risk for respiratory distress also are discussed.

Crying↗

PubMed1995

Durations of young children's word and nonword vocalizations.

The duration of word (W) and nonword (NW) forms was examined in the monthly vocalizations of seven children between 8 and 26 months of age. The W (i.e., glossable "adultlike") forms and NW (i.e., nonglossable but phonetically transcribable) forms occurring in each child's consonant+vowel (CV) vocalizations were measured. The results were that W durations significantly decreased as a function of increasing chronological age. On the other hand, NW durations were not correlated with increasing age. The meaningfulness corresponding to W forms is hypothesized to account for the results.

Child, Preschool↗

PubMed1993

Chronic otitis media and early speech development: a case study.

A case study of the speech development in a male infant with chronic otitis media is reported. The phonetic behavior characterizing the child's vocalizations was sampled monthly between the ages of 11 and 21 months, as he progressed from pre-speech to early speech periods of language development. Results of monthly phonetic inventory analyses indicated age-appropriate types of consonants in his pre-word and later-word vocalizations. However, the child's repertoire of consonants was considerably reduced as he first began to produce meaningful speech. Results of phonetic diversity analyses revealed an overall lack of phonetic complexity in his vocalizations throughout the course of study. In general, the child's early sound productions were characteristic of developmental delay, closely resembling the speech patterns found among severely hearing-imparied children. Findings are discussed with respect to the probable influence of chronic otitis media with effusion on a child's eventual speech development.

Chronic Disease↗

PubMed1992

Relative timing characteristics of hearing-impaired speakers.

Speech duration characteristics of phrase-level utterances produced by 26 severely and profoundly hearing-impaired adults were examined acoustically using relative timing measures. The measures were then compared to the same utterances produced by 13 normal-hearing adults. Although absolute speech durations of the hearing-impaired subjects were significantly longer than their normal-hearing counterparts, relative timing did not differ between groups. Findings are discussed in relation to the biological constraint hypothesis associated with speech timing, as well as the role of auditory feedback in models of speech production.

Adult↗

PubMed1990

Syllable durations of preword and early word vocalizations.

The continuity in development of syllable duration patterns was examined in 7 young children as they progressed from preword to multiword periods of vocalization development. Using a combination of lexical and chronological age points, monthly vocalization samples were analyzed for bisyllable duration and final syllable lengthening. Results revealed no systematic increase or decrease in the duration of bisyllables produced by the children as a group. Lengthening of final syllables was observed across nearly all recording sessions for all children. It is likely that the feature of bisyllable duration is not discernibly sensitive to changes associated with a developing speech mechanism and environmental input. On the other hand, the regularity in final syllable lengthening is consistent with a continuity theory of development.

Child↗

PubMed1990

Gender comparisons of children's vocal fold contact behavior.

Vocal fold contact behavior was examined in separate groups of boys and girls through application of an electroglottograph(EGG). In general, a contact quotient (EGG duty cycle) showed minimal differences within and between boys and girls during sustained production of the vowels /i/, /u/, and /a/. The findings are discussed with respect to the laryngeal behavior of prepubescent children as well as the clinical utility and applicability of the EGG for examining phonatory behavior among young children.

Child↗

PubMed1989

Vocal fundamental frequency characteristics during the first two years of life.

Vocal fundamental frequency (Fo) characteristics were sampled for a group of seven young children. The children were followed longitudinally for a 12-month period, spanning preword, single-word, and multiword vocalizations. The Fo characteristics were analyzed with reference to chronological age, vocalization length, and lexicon size. Measures of average Fo and Fo variability changed little during the 12-month period for each child. A rising-falling intonation contour was the most prevalent Fo contour among the children. In general, the influence of vocalization length and language acquisition on measures of Fo was negligible. It is suggested that relative uniformity in vocal Fo exists in early vocalizations across preword and meaningful speech periods.

Child, Preschool↗